[WP] There is a portal to an endless ocean, filled with monstrous beings. After repelling the initial ‘leaks’, humans explore this endless, sunless, sea.

The Russian’s Sierra-Class submarine Pskov was the only craft of the joint operation to survive the initial onslaught from the other world. The rotting corpse of an impossibly large sea beast floated onto the shore of Chile, drawing large crowds of horrified onlookers. World leaders were scrambling to organize a barrier of some sort, a sort of control zone to prevent further creatures from coming through. Captain Rohkscov had no patience for the bureaucracy, however. He had just taken the liberty of attaching cameras all over his vessel, to allow for better perception in an entire world of water draped in darkness.

“Ensign. Any contacts on sonar?” The question came from a steel-gray beard.

“No sir. Nothing.” The young man whispered, his clean-shaven face made him look like a 15 year old boy. He gulped nervously, louder than he expected to.

“Set a course, straight ahead half.” The crew murmured among themselves, looking to their captain.

“Sir?”

“Do it. We have to make sure nothing else gets through before reinforcements come. Its up to us, now.” Rohkscov said with an icy sternness. The crew began to work in unison, preparing for something no human had ever done before. The submarine lurched forward, and everyone on board held their breath. Even the captain.

A terrible creaking filled the ship as it neared the entrance. Tapping the monitor with the front camera feed, Rohkscov made sure everything was working. The water was a deep blue, but the portal was plain to the naked eye. Black as night, darker than space. It seemed to absorb light around it.

“A black hole…?” He muttered to himself. “Yellow alert.” He knew it didn’t matter. All that did was that he still had plenty of torpedoes left, and that the nuclear reactor was still functioning within normal parameters. The darkness grew and filled the camera feeds all around. Port and starboard feeds fell into the black. The collective heartbeats of the entire crew could almost be heard above the unnatural silence of this part of the ocean. Even the engine could scarcely be heard. And then a rushing sound of water roared around them, scaring the shit out of many an ensign. Even the captain felt uneasy despite his words.

“Steady, men. Steady.” The roaring filled the command deck, the steel around them creaking and shaking violently. With his hands clasped behind his back, he used all his might to stay on two feet as one officer fell from his post. The man clamored back into his chair, staring at the radar desperately while holding the console before him. The radar was registering a constant contact all around them, as if they were surrounded by a massive school of tuna that stretched forever.

Then silence. The ping of the radar was the only sound. The camera feeds remained dark as a moonless night in the woods of Siberia. Ping. Ping.

“Turn the floodlights on. Any radar contact?” Rohkscov hissed.

“No sir. Nothi — wait. One contact, dead ahead. It’s massive, sir. Just like the other contact.” The men were silent, staring at their monitors, resisting the urge to glance around themselves.

“Red alert! Load all the tubes, flood them with water. Prepare for a full attack.” Rohkscov’s heart pounded in his throat, and he tried hard to gulp it down. He knew this was a suicide mission. But he had to do what he could to prevent another invasion from this forgotten realm. He stared at the cameras, flicking on the floodlights. Nothing was there, at least not yet.

“Fire tubes 1 through 4! Then begin a dive!” Rohkscov wasn’t sure the hull could take this kind of pressure. The iron was already moaning all around them, complaining. Lugnuts strained to keep in place.

“Torpedoes away! Beginning the dive!” The ensign shouted. Men all around were shouting commands into their radios, bracing themselves for the maneuver.

“Dive Dive Dive!” Rohkscov held onto the periscope tower, as the entire deck tilted, and his eyes were glued to the camera. The torpedoes went true on their path, dead ahead. The explosions shot small light bursts into the feed, and he could see a body of something that should never be able to exist. As the sub turned down to dive, twisting to port, he could see a large… chest? Green among the inky black. The sub continued its dive, luring the creature after them as a terrible squeal filled the ocean of madness. The horror was palpable, the minds of men weak in such a strange place. One ensign was crying as he stared at his screen with a vacant face, dreaming of the Volga.

The sub continued its dive as the strange being screamed, echoing within the skulls of the crew. No matter how hard they pressed their hands into their ears they could hear it. The cries of an alien being. Further down they went, twisting and spiraling into the obsidian water. Rohkscov stared at his screens, listening to the sounds of rivets popping and steel squeaking in protest. Then he saw something. Structures. A forbidden acropolis. Unnatural angles, sloping stones. Escherian architecture.

“Impossible” Rohkscov whispered, and all the men were shouting as he stood staring at the screens. “What is this place?” The stones from which these eldritch buildings were carved was a dark obsidian blended with the green of emerald moss, and as the submarine continued its dive, found a massive opening in this hellish temple sitting amongst odd spheres and hateful geometry. Whispers filled his mind, words that violated his senses and penetrated his will. He fell to his knees, clutching his ears. The cries of the beast were nothing compared to those whispers! The darkness was so complete here, in this forgotten place. A place that should never have been discovered.

The submarine suddenly halted, throwing men to their faces and back, knocking the wind out of most. The whispers fell silent, and the sub began to move again. Rohkscov looked up from the ground, tears welling in his eyes as he stared at the front cameras. The chest. Horrible barnacles crusting powerful muscles. His view rose up to see a massive nest of twirling tentacles, writhing as if they all had minds of their own. The whispers began again as he saw the terrible maw of something older than his home world. And then the eyes. The eyes that seemed to stop his heart in his chest. He died before the submarine was crushed like a soda can in the hands of an elder god.